Occlusion balloon catheter and methods of fabrication and use

ABSTRACT

A balloon catheter assembly is provided with an outer catheter, an inner catheter, an outer adapter and a balloon, and is configured such that the balloon resides entirely within a predetermined volume having an outer diameter substantially equal to or less than the outside diameter of the distal end of the outer catheter when the balloon is in a deflated configuration. Methods of using and steering the catheter assemblies are also provided.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/044,864 filed Feb. 16, 2016. This application is related to U.S.application Ser. No. 14/273,445, entitled “Device and Methods forTransvascular Tumor Embolization with Integrated Flow Regulation”, filedMay 8, 2014, now U.S. Pat. No. 9,205,226.

INCORPORATION BY REFERENCE

All publications and patent applications mentioned in this specificationare incorporated herein by reference in their entirety to the sameextent as if each individual publication or patent application wasspecifically and individually indicated to be incorporated by reference.

FIELD

This application relates generally to medical methods and devices. Morespecifically, the present disclosure relates to devices and methods toaffix a balloon below the surface of a catheter and to achieve a lowprofile for entering small vasculature.

BACKGROUND

Catheters are commonly used in medicine for delivery of fluids,therapeutics and implants as well as in sampling tissues and bodilyfluids. Catheters can be constructed with balloons or other tools todilate tissue, block fluid flow or isolate segments of the anatomy. Arelatively common use for a catheter is the delivery of drugs to atarget tissue using blood vessels as a means of access. When a balloonis used, the vascular compartment distal to the balloon is isolated fromthe vascular compartment proximal to the balloon and perfusion ofdiagnostic, therapeutic or embolic agents is localized and concentrated.Transvascular catheters, especially in the peripheral blood circulation,need to have a small axial diameter to allow access into small vessels.

One common use for a microcatheter is the delivery of embolic agents andanticancer drugs to a tumor.

According to the NIH, 30,640 people were diagnosed with primary livercancer (hepatocellular carcinoma, HCC) and 142,820 people were diagnosedwith colorectal cancer in the US in 2013. Seventy five percent of thesewill metastasize to the liver. Liver resection and transplant are theonly curative means; however, only small numbers of patients areeligible. Systemic Chemotherapy for primary and metastatic tumors in theliver is ineffective, having a response rate of about 20% and a survivalbenefit of 10.7 months vs. 7.9 months over symptomatic care.

Trans-Arterial Embolization therapy is the transvascular injection ofdrug and/or embolic agents directly into, or in the vicinity of, thetumor vasculature using a microcatheter. Embolization therapy causes ashutdown of blood flow and, when drug or radioactivity is present,simultaneous release of high concentrations of drug or radioactivity.The technique is also noted for its very low level of toxicity.Chemoembolization was established as a standard of care for intermediatestage hepatocellular carcinoma in 2006.

Numerous studies have demonstrated transarterial embolization to beeffective on a number of primary cancers and to have better performancethan chemotherapy for both HCC and metastatic colorectal cancers in theliver; however, studies show inconsistent outcomes with reported tumorresponses from 15% to 85%. Although anatomical and individualdifferences are clearly of significance in between-patient variation,clinical studies, each of which include a range of patients, show verydifferent outcomes, indicating that procedural standardization isneeded.

The present state-of-the-art embolization therapy for tumors in theliver relies on high volume “forward flow” from the hepatic artery thatis flowing at about 6 ml/sec to deliver embolization agents into thetumor. As embolization progresses, the distal capillaries becomeoccluded and the tumor can no longer accept this high flow rate, eventhough the tumor is only partially filled with embolic agents. Tumorembolization using high volume flow from the unrestricted hepatic arterycauses: (1) rapid embolization of the distal portions of tumorcapillaries, (2) rapid onset of high intra-tumor pressure, (3) reflux ofblood and embolic agents from the tumor, (4) increased non-target flowinto hepatoenteric arteries, and (5) poor filling and distribution ofembolic agents in the tumor. This situation results in an uncontrollablenumber of particles or other embolic agents entering the tumor and highprocedural variability.

Although standardization to an optimal protocol should improvereproducibility and overall outcomes, the procedure is presently withoutoptimization or standardization. The current delivery catheters areunable to control many of the above mentioned variables, makingstandardization unlikely. There is a need for a delivery system thatenables a measurable clinical endpoint, a known quantity of embolicagent delivered, and elimination of non-target embolization. This is arequired first step if standardization is to be achieved.

As a requirement, a delivery catheter that would solve theaforementioned problems, must have a small radial diameter to allowaccess into small vessels that are typically in the vicinity of thetumor. Presently, balloons are bonded to the external surface of acatheter and necessarily increase its diameter. It would be asignificant advantage to construct a balloon catheter whereby a balloonwas positioned below the surface of the catheter when in its constrainedconfiguration and return thereto following inflation and deflation. Onemethod to accomplish this is to configure a circumferentially orientedpocket or pockets in a catheter whereby a balloon bonding surface ispositioned below the surface of the catheter. The present disclosure isa device and method that achieves a low profile catheter by positioningthe balloon bonding surfaces below the surface of a drug deliverycatheter.

U.S. patent application Ser. No. 10/128,977 describes a coaxial catheterwhereby a balloon is bonded to an elongated outer tube to prevent theballoon from telescopingly buckling when the balloon is being pushedacross a narrow passage. U.S. Pat. No. 6,066,157 describes a coaxialcoronary angioplasty catheter whereby an anchor joint is configured toallow distal movement of the inner tube and to prevent proximalmovement. U.S. Pat. No. 5,647,198 describes a catheter with a pair ofspaced apart balloons that define an intra-balloon space. A lumen passesthrough the catheter and exits within the intra-balloon space allowinginjection of drugs, emulsions, fluids and fluid/solid mixtures. Aperfusion lumen or bypass extends from a location proximal to theproximal balloon and to the distal tip to allow shunting of blood pastthe inflated balloons. U.S. Pat. No. 5,674,198 describes a two ballooncatheter that is designed for treating a solid tumor. The balloons arepositioned to isolate the blood flow into the tumor and allow injectionof a vaso-occlusive collagen material to block the tumor blood supply.Clifton et al. (1963) Cancer 16:444-452 describes a two balloon catheterfor the treatment of lung carcinoma. The four lumen catheter includes alumen for independent injection in the space between the balloons.Rousselot et al. (1965) JAMA 191:707-710 describes a balloon catheterdevice for delivering anticancer drugs into the liver. See also U.S.Pat. Nos. 6,780,181; 6,835,189; 7,144,407; 7,412,285; 7,481,800;7,645,259; 7,742,811; U.S. App. No. 2001/008451; U.S. App. No.2001/0041862; U.S. App. No. 2003/008726; U.S. App. No. 2003/0114878;U.S. App. No. 2005/0267407; U.S. App. No. 2007/0137651; U.S. App. No.2008/0208118; U.S. App. No. 2009/0182227 and U.S. App. No. 2010/0114021.

What is needed and is not provided in the prior art is a means ofpositioning of balloon bonding surfaces and attachment of a balloonbelow the surface of a catheter body and allow a low profile catheterthat is useful in providing therapy within small blood vessels.

SUMMARY OF DISCLOSURE

According to aspects of the present disclosure, devices are provided forattachment of a balloon or other vascular occlusion device or tool to acatheter whereby the device bonding surfaces are positioned below thesurface of the outer diameter of a catheter body. Such catheters areintended for many medical purposes, but the embodiments described hereinare focused on microcatheters intended to perform medical procedures insmall blood vessels within the body. Such a catheter can access thevascular system percutaneously from any convenient artery or veinincluding, but not limited to, the femoral artery, carotid artery orjugular vein.

In some embodiments of the present disclosure a device comprises anouter catheter, an inner coaxial catheter, an outer adapter, a supportsheath and a balloon. The inflatable balloon has an inner surface thatat least partially defines an interior volume. The balloon also has aproximal surface and a distal surface and a channel that extendslongitudinally through the balloon, said channel is configured toprovide fluid communication between the proximal surface of the balloonand the distal surface of the balloon. The outer catheter has a proximalend, a distal end and a lumen that extends therethrough. The innercatheter is a smaller diameter than the outer catheter and has aproximal end, a distal end and a lumen extending therethrough. The innercatheter is positioned inside the outer catheter, thereby forming anannular space between the inner and outer catheter, said annular spaceis in fluid communication with the inner volume of the balloon andprovides a lumen for balloon inflation and deflation. The inner catheterextends distally for some distance beyond the distal end of the outercatheter, providing a reduced diameter whereby a balloon or otheraccessory can be circumferentially disposed at a level that is below theouter catheter. At its distal end, the balloon can be bonded to theextension of the inner catheter. The proximal end of the balloon isattachable to the distal end of the outer catheter using the adapter andsupport sheath of the present disclosure and allows the balloon to bebonded below the surface of the outer diameter of the outer catheterwith a channel extending from the distal end of the catheter assembly tothe inner volume of a balloon and, if needed, close abutment of theproximal end of the balloon to the distal end of the outer catheter. Inthis instance, the proximal end of the adapter is larger in diameterthan the distal aspect and is attached to outer distal end of the outercatheter, typically in a manner that positions the proximal adapterbelow the surface of the distal outer catheter. The distal aspect of theadapter has a smaller diameter than the proximal aspect, whereby theouter surface of the distal aspect of the adapter is positioned belowthe surface of the outer catheter and a balloon can be bonded to theouter surface of the distal aspect of the adapter, thereby positioningthe balloon bonding surface below the outer catheter surface. Theproximal portion of a support sheath can be attached circumferentiallyto the outer surface of the distal outer catheter, typically in a mannerthat positions the sheath below the surface of the distal outer catheterand the distal portion of the sheath is positioned over the proximal endof the balloon. One advantage of the sheath of the present disclosure isto hold the proximal balloon to the distal adapter and therebystrengthening the balloon attachment. Advantages of the device of thepresent disclosure include a balloon with at least one bond below theouter surface of an outer catheter, providing a low profile, a strongbonding of the balloon to the catheter assembly and rapid inflation anddeflation of a balloon, even with viscous solutions such as radiopaquecontrast media.

In some embodiments of the present disclosure, the device comprises anouter catheter, an inner coaxial catheter, a sheath, an inner adapterand a balloon. The outer catheter has a proximal end, a distal end and alumen that extends therethrough. The inner catheter is a smallerdiameter than the outer catheter and has a proximal end, a distal endand a lumen extending therethrough. An inflatable balloon has an innersurface that at least partially defines an interior volume. The balloonalso has a proximal surface and a distal surface and a channel thatextends longitudinally through the balloon, said channel is configuredto provide fluid communication between the proximal surface of theballoon and the distal surface of the balloon. The inner catheter ispositioned inside the outer catheter, thereby forming an annular spacebetween the inner and outer catheter, said annular space is in fluidcommunication with the inner volume of the balloon and provides a lumenfor balloon inflation and deflation. The inner catheter extends distallyfor some distance beyond the distal end of the outer catheter, providinga reduced diameter whereby a balloon or other accessory can becircumferentially disposed at a level that is below the outer catheter.At its distal end, the balloon can be bonded to the extension of theinner catheter. The balloon is attachable to the distal end of the outercatheter using the an inner adapter and sheath of the present disclosurewhich allow the distal balloon bond to be positioned below the surfaceof the outer diameter of the outer catheter and, if needed, closeabutment of the proximal end of the balloon to the distal end of theouter catheter. In this instance, the proximal end of the adapter isattached to the inner lumenal surface of the distal end of the outercatheter. The proximal portion of the support sheath is attached to theouter surface of the distal outer catheter, typically in a manner thatpositions the sheath below the surface of the distal outer catheter andthe distal portion of the sheath is positioned over the proximal end ofthe balloon, whereby it may or may not be affixed. Advantages of theadapter are to provide a bonding surface for a balloon that is below thesurface of a catheter assembly and provide an annular inflation channelwhich allows the balloon to inflate and deflate rapidly, even withviscous fluids such as contrast media. An advantage of the supportsheath of the present disclosure is to hold the proximal balloon to theadapter and thereby strengthening the balloon attachment.

In some embodiments of the present disclosure, a device comprises a twolumen catheter, a support sheath, an outer adapter and a balloon. Theinflatable balloon has an inner surface that at least partially definesan interior volume. The balloon also has a proximal surface and a distalsurface and a channel that extends longitudinally through the balloon,said channel is configured to provide fluid communication between theproximal surface of the balloon and the distal surface of the balloon.The two lumen catheter has a proximal end, a distal end and two lumens,a first injection lumen that is in fluid communication with the distalend of the catheter and provides a channel to deliver therapeutic agentsto a target tissue or aspirate fluids for analysis and a second lumenthat is in fluid communication with the interior surface of the balloonand provides for inflation and deflation. The first injection lumentypically extends for some distance distally beyond the end of theinflation lumen and provides a reduced diameter for circumferentialattachment of a balloon or other accessory. The balloon is attachable tothe distal end of the catheter using the adapter and sheath of thepresent disclosure in a manner that positions the balloon bondingsurfaces and, if desired, the balloon outer diameter, below the surfaceof the outer diameter of the outer catheter and, if needed, closeabutment of the proximal end of the balloon to the distal end of thecatheter. Although it is typically desirable that the balloon outerdiameter be positioned below the outer diameter of the catheter, in someinstances it may be desirable for the balloon to extendcircumferentially outward beyond the outer diameter of the catheter. Inthis instance, the proximal end of the adapter is larger in diameterthan the distal aspect, whereby the inner surface of the balloon isbonded to the outer surface of the distal aspect of the adapter and theinner surface of the proximal aspect of the adapter is attached todistal end of the outer catheter, typically in a manner that positionsthe proximal adapter substantially below the surface of the distal outercatheter. The proximal portion of a support sheath is attached to theouter surface of the distal outer catheter, typically in a manner thatpositions the support sheath substantially below the surface of thedistal outer catheter and the distal portion of the sheath is positionedover the proximal end of the balloon and may, if desired, be bondedthereto. The distal end of the balloon can then be affixed to theextension of the first lumen whereby the bonding surfaces of the balloonare positioned below the surface of the largest diameter of the catheterassembly. One advantage of the sheath of the present disclosure is tohold the proximal balloon to the distal adapter and therebystrengthening the balloon attachment and compressing the bond joint tominimize size. Advantages of the adapter of the present disclosure areto position the balloon bonding areas below the surface of a catheterassembly and to provide a substantially circumferential ballooninflation area that can allow rapid and substantially symmetricalinflation and deflation, even with viscous solutions such as radiopaquecontrast media.

In some embodiments of the present disclosure a nose piece, nose cone,marker band or other similar structure is positioned circumferentiallyabout an extension of the inner catheter or injection lumen and distalto the distal end of the balloon inflation lumen, whereby the proximalend the balloon is bonded according to the present disclosure below thesurface of the catheter and the distal end of the balloon can be bondeddirectly to the distal extension or to the nose piece using the deviceof the present disclosure, provided that all balloon bonding surfacesare below the outer diameter of the catheter assembly. In this instance,a pocket is formed between the distal catheter and the proximal end ofthe nose piece.

In some embodiments of the present disclosure a device comprises a firstouter catheter, a second outer catheter, an inner coaxial catheter, atleast one outer or inner adapter, at least one support sheath and aballoon. The inner catheter is positioned inside the outer catheter,thereby forming an annular space between the inner and outer catheter,said annular space is in fluid communication with the inner volume ofthe balloon and provides a lumen for balloon inflation and deflation.The inner catheter extends distally for some distance beyond the distalend of the first outer catheter, providing a reduced diameter, whereby aballoon or other accessory can be circumferentially disposed at a levelthat is below the outer catheter. The second outer catheter isconfigured such that it can be circumferentially oriented about thedistal extension of the inner catheter at some distance from the distalend of the first outer catheter to form a pocket between the distal endof the first outer catheter and the second outer catheter. For thepurpose of this embodiment, the first outer catheter and the secondouter catheter are of the same diameter, however, the first outercatheter and the second outer catheter need not have the same diameter.A balloon is oriented circumferentially about the inner catheter at aposition that is distal to the first outer catheter and proximal to thesecond outer catheter and within a pocket formed therebetween. Theproximal end the balloon is bonded according to the present disclosurebelow the surface of the first outer catheter and the distal end of theballoon can be bonded directly to the distal extension or to the secondouter catheter using the device of the present disclosure, provided thatall balloon bonding surfaces are below the outer diameter of thecatheter assembly.

In some embodiments of the present disclosure an adapter is positionedat the proximal end of the balloon, the distal end of the balloon, orboth proximal and distal ends of the balloon or an adapter is notpresent at either the proximal or distal ends of the balloon with therequirement that there is at least one adapter or one sheath at eachballoon bonding location. In this instance, when an adapter in notpresent, the outer surface of the balloon is bonded to the inner surfaceof the sheath.

In some embodiments a sheath is positioned at the proximal end of theballoon, the distal end of the balloon, or both proximal and distal endsof the balloon or a sheath is not present at either the proximal ordistal end of the balloon with the requirement that there is at leastone adapter or sheath at each bonding location. In this instance, whenan adapter in not present, the outer surface of the balloon is bonded tothe inner surface of the sheath.

In some embodiments the sheath is positioned on the distal and/orproximal balloon and does not extend over the outer catheter and/or nosepiece.

In some embodiments the sheath is replaced by a thread, clamp, band orother circumferential restraining device that is tightly wrapped aboutthe balloon segment that is over the adapter.

In some embodiments, a balloon catheter assembly is provided with anouter catheter, an inner catheter, an outer adapter, a balloon and asupport sheath. The outer catheter has a proximal end and a distal end,and the distal end has a wall thickness. The outer catheter comprises atleast two layers including a reinforcing layer and a base layer whichmay be less rigid. The inner catheter is located coaxially within alumen of the outer catheter, and the inner catheter has an injectionlumen extending therethrough. The inner and outer catheters form aninflation lumen therebetween. The outer adapter has a proximal end and adistal end. The proximal end is sized to fit over an outside diameter ofthe distal end of the outer catheter and configured to be affixedthereto. The distal end of the outer adapter has a reduced outerdiameter that is smaller than an outside diameter of the distal end ofthe outer catheter. The distal end of the outer adapter has an insidediameter that is larger than an outside diameter of the inner catheter,thereby forming a fluid channel therebetween that is in fluidcommunication with the inflation lumen. The outer adapter has a singlelayer and is formed of a material that is different from that of theouter catheter base layer. The outer adapter has a wall thickness thatis no more than 15% of the wall thickness of the distal end of the outercatheter. The balloon has a proximal end with an inner surface affixedto the reduced outer diameter of the outer adapter, and the balloon hasa distal end with an inner surface affixed to the outside diameter ofthe inner catheter. The balloon has an interior space that is in fluidcommunication with the fluid channel. The support sheath has a proximalend positioned over an outside diameter of the outer adapter and adistal end positioned over an outside diameter of the proximal end ofthe balloon. The support sheath is composed of a single layer, beingformed of a material substantially the same as the material of the outeradapter, and having a wall thickness substantially the same as the wallthickness of the outer adapter. The balloon resides entirely within apredetermined volume having an outer diameter substantially equal to orless than the outside diameter of the distal end of the outer catheterwhen the balloon is in a deflated configuration. The balloon can beinflated by introducing a fluid through the inflation lumen and fluidchannel into the interior space of the balloon. The balloon can then bedeflated by removing the fluid from the interior space such that theballoon returns entirely within the predetermined volume.

In some of the above embodiments, the inner catheter has a distal endthat extends distally beyond the distal end of the balloon. The ballooncatheter assembly may further comprise a nosecone located on the distalend of inner catheter distal to the balloon, the nosecone having anouter diameter substantially equal to the outside diameter of the distalend of the outer catheter such that the balloon is recessed in a pocketformed between the nosecone and the outer catheter when the balloon isin the deflated configuration. The balloon catheter assembly may furthercomprise a proximal bond that affixes the inner surface of the proximalend of the balloon to the reduced outer diameter of the outer adapter,and a distal bond that affixes the inner surface of the distal end ofthe balloon to the outside diameter of the inner catheter. In someembodiments, both the proximal bond and the distal bond are locatedradially inward from the outside diameter of the distal end of the outercatheter. In some embodiments, both the proximal bond and the distalbond are located radially inward from an inside diameter of the distalend of the outer catheter. The inflation lumen may have a substantiallyannular cross-section. The outer catheter may comprise a base materialand a different reinforcing material, and the outer adapter may be madeof a plastic polymeric material. The reduced outer diameter portion ofthe outer adapter may have a wall thickness less than 0.01 mm. In someembodiments, the support sheath has a length that is at least as greatas the outside diameter of the distal end of the outer catheter.

In some embodiments, methods of using a balloon catheter assembly areprovided. The method may include providing a balloon catheter assemblyhaving an outer catheter, an inner catheter, an outer adapter, a balloonand a support sheath. The outer catheter has a proximal end and a distalend, and the distal end has a wall thickness. The outer catheter has atleast two layers including a reinforcing layer and a base layer whichmay be less rigid. The inner catheter is located coaxially within alumen of the outer catheter, and the inner catheter has an injectionlumen extending therethrough. The inner and outer catheters form aninflation lumen therebetween. The outer adapter has a proximal end and adistal end, the proximal end being sized to fit over an outside diameterof the distal end of the outer catheter and configured to be affixedthereto. The distal end of the outer adapter has a reduced outerdiameter that is smaller than an outside diameter of the distal end ofthe outer catheter. The distal end of the outer adapter has an insidediameter that is larger than an outside diameter of the inner catheter,thereby forming a fluid channel therebetween that is in fluidcommunication with the inflation lumen. The outer adapter has a singlelayer and is formed of a material that is different from that of theouter catheter base layer. The outer adapter has a wall thickness thatis no more than 15% of the wall thickness of the distal end of the outercatheter. The balloon has a proximal end with an inner surface affixedto the reduced outer diameter of the outer adapter, and has a distal endwith an inner surface affixed to the outside diameter of the innercatheter. The balloon has an interior space that is in fluidcommunication with the fluid channel. The support sheath has a proximalend positioned over an outside diameter of the outer adapter and adistal end positioned over an outside diameter of the proximal end ofthe balloon. The support sheath is composed of a single layer, beingformed of a material substantially the same as the material of the outeradapter, and has a wall thickness substantially the same as the wallthickness of the outer adapter.

The above methods may further include inserting a distal end of theballoon catheter assembly into a blood vessel of a body, and inflatingthe balloon by introducing a fluid through the inflation lumen and fluidchannel into the interior space of the balloon to at least partiallyocclude blood flow in the blood vessel. The methods may also includeinjecting a substance into the blood vessel through the injection lumen,deflating the balloon by removing the fluid from the interior space ofthe balloon such that the balloon returns entirely within apredetermined volume having an outer diameter substantially equal to orless than the outside diameter of the distal end of the outer catheter,and withdrawing the distal end of the balloon catheter assembly from theblood vessel.

In some of the above methods, the inner catheter may have a distal endthat extends distally beyond the distal end of the balloon. The ballooncatheter assembly may further comprise a nosecone located on the distalend of inner catheter distal to the balloon, the nosecone having anouter diameter substantially equal to the outside diameter of the distalend of the outer catheter such that the balloon is recessed in a pocketformed between the nosecone and the outer catheter when the balloon isin the deflated configuration. The balloon catheter assembly may furthercomprise a proximal bond that affixes the inner surface of the proximalend of the balloon to the reduced outer diameter of the outer adapter,and a distal bond that affixes the inner surface of the distal end ofthe balloon to the outside diameter of the inner catheter. In someembodiments, the proximal bond and the distal bond are located radiallyinward from the outside diameter of the distal end of the outercatheter. In some embodiments, both the proximal bond and the distalbond are located radially inward from an inside diameter of the distalend of the outer catheter. The inflation lumen may have a substantiallyannular cross-section. The outer catheter may comprise a base materialand a different reinforcing material, and the outer adapter may be madeof a plastic polymeric material. In some embodiments, the reduced outerdiameter portion of the outer adapter has a wall thickness less than0.01 mm. The support sheath may have a length that is at least as greatas the outside diameter of the distal end of the outer catheter.

In some embodiments, methods of steering a balloon catheter assembly areprovided. The methods may include providing a balloon catheter assembly,the assembly comprising a catheter body having a proximal end and adistal tip portion, and a balloon affixed near the distal tip portion.The balloon may have an interior space that is in fluid communicationwith an inflation lumen extending from the balloon towards the proximalend of the catheter body. The methods may also include inserting thedistal tip portion of the balloon catheter assembly into a blood vesselof a body, and inflating the balloon by introducing a fluid through theinflation lumen into the interior space of the balloon sufficient tolaterally deflect the distal tip portion from a longitudinal axis of thecatheter body. The catheter assembly is then advanced through the bloodvessel in the direction of the deflected distal tip portion.

In some of the above methods, the advancing step comprises advancing thedistal tip portion from the blood vessel into a branch vessel. Themethods may also comprise extending a guidewire from the distal tipportion before the advancing step, and then advancing the distal tipover the extended guidewire. The methods may comprise locating a distalend of a guidewire within the catheter body at a point adjacent to theballoon before deflecting the distal tip portion. The methods maycomprise rotating the catheter body axially after deflecting the distaltip portion such that the tip portion is pointed in a desired direction.

While aspects of the present disclosure will be described withparticular reference to attachment of a balloon to a distal location ona catheter, the same principle can be applied to the attachment of anydevice that is positioned below the surface of a catheter.

BRIEF DESCRIPTION OF THE DRAWINGS

Novel features of the disclosure are set forth with particularity in theclaims that follow. A better understanding of the features andadvantages of the present disclosure will be obtained by reference tothe following detailed description that sets forth illustrativeembodiments, in which principles of the disclosure are utilized, and theaccompanying drawings (which are not necessarily shown to scale) ofwhich:

FIG. 1 is a longitudinal cross section of one embodiment of the presentdisclosure with balloon bonds below the surface of the outer catheter;

FIG. 2 is an axial cross section of a coaxial catheter;

FIG. 3 is a longitudinal view of a coaxial catheter assembly;

FIG. 4A is a side view of an outer adapter component;

FIG. 4B is a side view of an inner adapter component;

FIG. 4C is a side view of a support sheath component;

FIG. 5A is a longitudinal cross section of one embodiment of the presentdisclosure including a nose cone;

FIG. 5B is an enlarged view of the distal end of the catheter shown inFIG. 5A;

FIG. 6A is a longitudinal cross section of an embodiment of the presentdisclosure including a second outer catheter;

FIG. 6B is an enlarged view of the distal end of the catheter shown inFIG. 6A;

FIG. 7A is a longitudinal cross section of an embodiment of the presentdisclosure including an inner adapter;

FIG. 7B is an enlarged view of the distal end of the catheter shown inFIG. 7A;

FIG. 8A is a longitudinal cross section of a fourth embodiment of thepresent disclosure including a two lumen catheter;

FIG. 8B is an enlarged view of the distal end of the catheter shown inFIG. 8A;

FIG. 9A is a side view of a catheter balloon inflated to the extent thatit laterally deflects the distal tip of the catheter for steering;

FIG. 9B is the same as FIG. 9A with markings added to show variousdeflection angles.

DETAILED DESCRIPTION

A standard microcatheter for drug delivery is designed to access smallvasculature and necessarily has a small outer diameter in the range of0.5 mm to 2 mm more optimally 0.75 mm to 1 mm. For use in the peripheralvasculature, and in particular for tumor embolization, deliverycatheters are typically 75 cm to 175 cm in length. Once the catheter isoriented at a target site within the blood vessel, drug, embolic agents,contrast or other fluids are injected through a lumen that extendslongitudinally from proximal to distal ends. It is common that thefluids are viscous and must be injected at high flow rates in the rangeof 1 ml/second to 10 ml/second. However, flow rate is limited byinjection lumen diameter or cross sectional area, length and the abilityof the catheter wall to withstand high pressures in the range of 250 psito 2000 psi, more typically in the range of 500 psi to 1,500 psi. Giventhat the catheter length is fixed by the requirements of thetransvascular procedure, flow rate can be maximized by making theinjection lumen and injection pressure tolerance as high as possible.

When considering a balloon microcatheter, an additional lumen thatextends longitudinally from proximal to distal ends of the catheter isadded for balloon inflation and deflation. In many embodiments, it isoptimal for the balloon to inflate and deflate in as short a time aspossible and in the range or 10 seconds to a maximum of 60 seconds. Whenballoons occlude or dilate blood vessels, it can be necessary fordeflation to occur rapidly to avoid complications. Often the balloon isinflated with radiopaque contrast which is a viscous fluid. Therefore,it is desirable that the balloon inflation lumen also be as large aspossible.

Since microcatheters have small cross sections, it is a challenge toachieve both rapid drug injection speed, which favors large injectionlumen size, and rapid balloon inflation and deflation times, which favorlarge balloon lumens.

Further, it would be highly desirable for the mounted balloon not toincrease the outer diameter of the catheter since it needs to maintain asmall profile and it is optimal to mount the balloon so that in itsretracted configuration it does not extend beyond the outer diameter ofthe catheter.

Transvascular microcatheters should also be flexible, most importantlyat the location of the balloon which is mounted at the distal portion ofthe catheter to allow them to advance through tortuous vasculature.Balloon bonding adhesives tend to be rigid and measures should be takento construct the balloon bonding surfaces to be flexible.

Therefore, in many embodiments, optimal characteristics of a balloonmicocatheter include: 1) a large drug injection lumen, 2) a largeballoon inflation lumen, 3) a catheter that withstands high pressure,and 4) a flexible distal catheter portion.

Strong bonding of the balloon to the catheter is also important toprevent detachment during a medical procedure and to assure that postinflation, the balloon can return to a position below the surface of theouter diameter of the catheter.

The methods and devices disclosed herein solve the aforementionedchallenges and enable a balloon microcatheter to be adapted to include alarge injection lumen, a large balloon inflation lumen, a flexibledistal catheter portion and strong balloon bonding that assure theballoon will return to a retracted diameter less than that of thecatheter's outer diameter.

The device of the present disclosure provides a means to affix a balloonto a catheter such that the balloon bonds are positioned below thesurface (i.e. radially inward of the outside diameter) of the catheterassembly and, if desired, the balloon in its uninflated configurationcan be positioned below the outer surface of the catheter assembly. Thepresent device allows a balloon to be inflated from below the surface ofa catheter assembly and when deflated, return thereto. Such a ballooncatheter assembly, as disclosed herein, has a small profile, a strongattachment of the balloon to the catheter and rapid inflation anddeflation times even with viscous solutions.

Referring to FIG. 1, a longitudinal cross section of the distal end ofone embodiment of the present disclosure is shown with catheter assembly2, outer catheter 4, inner catheter 6, inner catheter extension 8, outeradapter 10, support sheath 12, balloon 14, inner catheter lumen 16,annular lumen 18, fluid channel 20, proximal balloon bond 22, and distalballoon bond 24. In this embodiment, a coaxial catheter design is shownwith outer catheter 4, having a proximal end and a distal end and adiameter larger than inner catheter 6, also having a proximal end and adistal end, whereby inner catheter 6 is positioned longitudinally insideof outer catheter 4. Inner catheter 6 extends distally beyond the distalend of outer catheter 4, as indicated by extension distance 8, saidinner catheter extension providing a reduction in diameter whereupon aballoon or accessory can be attached.

Inner catheter 6 and outer catheter 4 are each typically composed of alaminate or composite of at least two layers, with a steel or otherbraid, coil, woven, and/or reinforcing material positioned between thelayers or forming one of the layers. In some embodiments, a reinforcingmaterial is molded within a less rigid base material such that thereinforcing layer is embedded in an encapsulation layer. Thisconstruction is provided to allow kink resistance and strength towithstand high pressure injection. Given the multi-layer construction,these walls typically have a thickness of 0.1 mm to 1 mm which consumesradial area which could otherwise be used to increase the size of theinjection lumen or balloon inflation lumen. Therefore, thin wallconstruction is optimal, provided that strength, kink resistance and atolerance to high pressure is maintained. In this exemplary embodiment,outer adapter 10 is composed of a single layer flexible material such asPebax, polyamide, polyethylene, polyurethane or the like and has a wallthickness of 0.0001 mm to 0.01 mm, more typically 0.001 mm to 0.0050 mm,said thickness being less than that of the inner catheter or outercatheter. In some embodiments, the outer catheter 4 has a wall thicknessof about 0.0635 mm and the outer adapter 10 has a wall thickness ofabout 0.00635 mm. In some embodiments, the wall thickness of the outeradapter 10 is no more than about 15% of the wall thickness of the outercatheter 4. The thickness and material type is different from that ofthe outer catheter and optimized for maximizing balloon inflation andinjection lumen diameters, flexibility and bondability of the balloonmaterial to the adapter.

The proximal end of outer adapter 10 is circumferentially oriented aboutthe outer surface of the distal end of outer catheter 4 and stepscentrally to a reduced diameter at a point distal to the distal end ofouter catheter 4, said reduced diameter is circumferentially orientedabout inner catheter 6. At its proximal end, support sheath 12 ispositioned over the distal end of outer catheter 4 and the proximal endof outer adapter 10, and the distal end of support sheath 12 ispositioned over the proximal end of balloon 14. Support sheath 12compresses the proximal end of balloon 14 into the space below the otherdiameter of outer catheter 4, assuring that the balloon will return to aposition below the outer diameter of outer catheter 4 and strengthensballoon bond 22 on outer adapter 10. In this exemplary embodiment,support sheath 12 is composed of a single layer flexible material withsubstantially the same wall thickness and material composition as theouter adapter 10.

The proximal end of inner catheter 6 is in fluid communication with thedistal end of inner catheter 6 by way of inner catheter lumen 16. Aspace between outer catheter 4 and inner catheter 6 defines a generallyannular lumen 18, and a space between the reduced diameter of outeradapter 10 and inner catheter 6 defines fluid channel 20. Balloon 14 isbonded at its proximal end to the reduced diameter of outside adapter 10by proximal balloon bond 22, and the distal end of balloon 14 is bondedto inside catheter 6 at distal balloon bond 24, such that proximalballoon bond 22 and distal balloon bond 24 are radially inward from theoutside diameter of outer catheter 4. In this exemplary embodiment,proximal balloon bond 22 and distal balloon bond 24 are also radiallyinward from the inside diameter of outer catheter 4, as shown in FIG. 1.The proximal end of catheter assembly 2 is in fluid communication withthe interior volume of balloon 16 by way of annular lumen 18, and fluidchannel 20. In some embodiments, inner catheter 6 may be located in anoffset manner within outer catheter 4 such that the inflation lumenformed therebetween is crescent-shaped rather than annular.

The aforementioned disclosure enables a balloon microcatheter to beadapted to an optimal: small outer diameter for use in small vessels,flexibility to navigate in tortuous vasculature, high pressure toleranceto allow high flow rates of drug and contrast, short balloon inflationand deflation times, balloon bondability, balloon bond strength andmaintenance of the balloon outer diameter to remain below the outerdiameter of the outer catheter, even after balloon inflation anddeflation.

Referring to FIG. 2 an axial cross section of a coaxial catheterassembly with outer catheter 4, inner catheter 6, inner catheter lumen16 and annular lumen 18 defining a space between outer catheter 4 andinner catheter 6. Inner catheter lumen 16 extends from the proximal endof the outer catheter 4 to the distal end of the outer catheter 4 andallows fluid communication therebetween. Annular lumen 18 extends fromthe proximal end of the catheter assembly to the inner volume of aballoon and allows fluid communication to inflate and deflate theballoon.

Referring to FIG. 3, a longitudinal cross section of catheter assembly30 is shown with outer catheter 4, inner catheter 6, inner catheterlumen 16, annular lumen 18, inner catheter extension 32, externalcatheter surface 34, internal catheter surface 36 (i.e. a portion of theinside diameter of outer catheter 4), inner balloon surface 38 and outerballoon surface 40. Outer catheter 4 has a diameter greater than innercatheter 6 and has a length that is less than that of inner catheter 6.Annular lumen 18 defines a space between outer catheter 4 and innercatheter 6 and extends from the proximal end of catheter assembly 30 tothe inner volume of balloon 14 and allows fluid communication to inflateand deflate the balloon. Inner catheter 6 has a length that is greaterthan that of outer catheter 4 and a lumen 16 that extends from theproximal end of catheter assembly 30 to the distal end of catheterassembly 30 and allows fluid communication therebetween. Inner catheterextension 32 with a diameter less than that of outer catheter 4,provides a surface whereby a balloon or other accessory can be attachedwith the bonding surfaces below the surface of (i.e. radially inwardfrom the outside diameter of) outer catheter 4 and, if desired, theballoon or other accessory can be positioned such that its outerdiameter is below the surface of outer catheter 4. In some embodiments,the balloon bonding surface may also be radially inward from the insidediameter of outer catheter 4. External catheter surface 34 defines acircumferential area on the outside of the distal end of outer catheter4 whereupon adapters and sheaths can be affixed, and internal cathetersurface 36 defines a circumferential area on the inside of the distalend of outer catheter 4 whereon adapters can be affixed. The diametersof external catheter surface 34 and internal catheter surface 36 areequal to the outer diameter and inner diameter of the catheter selected,respectively, typically from 0.3 mm to 5 mm, and the longitudinal lengthof the fixation surfaces can be from 0.2 mm to 25 mm, more typicallyfrom 1 mm to 10 mm.

Referring to FIG. 4A, a longitudinal cross section of an outer adapter10 is shown with a diameter reduction between a large diameter surface42 and a small diameter surface 44. Although outer adapter 10 shows asingle step from large diameter surface 42 to small diameter surface 44,the transition can be configured with 2, 3, 4 or more steps or thetransition can be a gradual as in a conical adapter. The outer adapter10 provides a connection between the external catheter surface 34, ofouter catheter 4 and an inner balloon surface 38 of balloon 14,providing fluid communication between the annular lumen 18 and the innersurface of balloon 14, whereby a proximal balloon bond is positionedbetween inner balloon surface 38 of balloon 14 and small diametersurface 44 of outer adapter 10, positioning the balloon bond below thesurface of the outer diameter of outer catheter 4. In some embodiments,the outer adapter 10 is made from a plastic polymeric material such aspolyester, nylon, Pebax, polyethylene, polyurethane, or other convenientmaterial. In many embodiments, a thin wall is preferred; however anythickness can be used depending on the application. Material thicknesswill typically range from 0.0003 mm to 1 mm, more typically from 0.003mm to 0.01 mm. The large diameter surface 42 of outer adapter 10 istypically glued, heat bonded, compressed or reflowed into the externalcatheter surface 34 of outer catheter 4. Reflow has the advantage thatlarge diameter surface 42 of outer adapter 10 melts into the outersurface of outer catheter 4 at external catheter surface 34 and does notincrease the diameter of outer catheter 4. The diameters of the largediameter surface 42 and the small diameter surface 44 will be dependenton the catheter diameter and the desired positioning of the balloonbonding surface below the outer diameter of outer catheter 4. Typicallythe outer diameter of medical catheters range from about 0.25 mm to 10mm, more typically from 0.5 mm to 5 mm, thereby making the largediameter surface 42 of the outer adapter 10 range from about 0.5 mm to 4mm. The outside adapter 10 can be any length of convenience, typically 2mm to 25 mm, more typically 4 mm to 10 mm. The outer adapter 10 of thepresent disclosure is particularly useful in micro-catheters thatcommonly have small outer diameters in the range of 0.5 mm to 1.5 mm andare used for access into the peripheral vasculature and into small bloodvessels. In this instance, it is important to keep the outer diameter ofthe catheter as small as possible. If a balloon or other accessory isplaced on the catheter, it can be a significant advantage to bond orotherwise mount the accessory below at least the outer surface of outercatheter 4. In addition to a balloon, an accessory can include a tissueanchor, blade, mechanical occlusion device, partial occlusion device, adevice to trap embolic particles, or any device of use in thevasculature.

Referring to FIG. 4B, a longitudinal cross section of an inner adapter46 is shown with a diameter reduction between a large diameter surface48 and a small diameter surface 50. In some embodiments, inner adapter46 is used instead of outer adapter 10. Although inner adapter 46 showsa single step from large diameter surface 48 to small diameter surface50, the transition can be configured with 2, 3, 4 or more steps or be agradual transition as in a conical adapter. The inner adapter provides aconnection between the internal catheter surface 36 of an outer catheter4 and balloon 14 at inner balloon surface 38, thereby positioning theballoon bonding surface or accessory attachment surface below the outersurface and the inner surface of outer catheter 4. The composition,measurements, use and benefits are as stated for FIG. 4A.

Referring now to FIG. 4C, a longitudinal cross section of a supportsheath 12 is shown with a proximal end, a distal end, an outer surface54 and an inner surface 56. The support sheath 12 fits circumferentiallyover the outer catheter 4 at external catheter surface 34 and balloon 14at outer balloon surface 40. Support sheath 12 functions to strengthenthe balloon bond and, if desired, hold the proximal end of balloon 14 ator below the outer surface of outer catheter 4. The length from proximalto distal ends of the support sheath is typically from 1 mm to 10 mm,more typically from 3 mm to 6 mm and any portion of the length can bebonded to the catheter with the remainder extended over the balloon orother accessory. In some embodiments, the support sheath has a lengththat is at least as great as the outside diameter of the distal end ofthe outer catheter. Typically the support sheath 12 is compressed,glued, reflowed or otherwise affixed to the outer catheter and extendsover, but may not be attached to a balloon or other accessory. In someembodiments, the support sheath is made from polymeric material such assilicone, latex, polyester, nylon, Pebax, polyethylene, polyurethane, orother convenient material. In many embodiments, a thin wall ispreferred, however, any thickness can be used depending on theapplication. Optimally the support sheath 12 is a heat shrink materialthat is placed at a desired position over the catheter and balloon, orother accessory, and heated, causing the material to reduce in diameterand compress about the surface of the outer catheter 4 and balloon 14.The thickness will typically range from 0.003 mm to 0.05 mm, moretypically from 0.006 mm to 0.01 mm. Reflow and compression have theadvantage that the outer surface 54 of the support sheath 12 melts or iscompressed into the outer surface of the outer catheter 4 and does notincrease the diameter of the outer catheter. The diameter of supportsheath 12 is dependent on the catheter diameter. Typically the outerdiameter of medical catheters range from about 0.5 mm to 5 mm.

Referring now to FIGS. 5A and 5B, a longitudinal cross section of asecond embodiment of the present disclosure is shown with catheterassembly 58, outer catheter 4, inner catheter 6, outer adapter 10, largediameter surface 42, small diameter surface 44, support sheath 12, nosecone 60, fluid channel 20, balloon 14, proximal balloon bond 22 anddistal balloon bond 24. External catheter surface 34 of catheter 4 isbonded to the inner surface of the large diameter surface 42 of adapter10. The inner surface of balloon 14 is bonded at its proximal end to theouter surface of small diameter surface 44 of adapter 10, at proximalballoon bond 22 and its distal end is bonded to inner catheter 6 atdistal balloon bond 24 that is positioned proximal to nose cone 60.Support sheath 12 is positioned such that it extends over externalcatheter surface 34 of outer catheter 4 and the proximal end of balloon14. The proximal end of support sheath 12 can be bonded, reflowed,compressed or otherwise affixed to external catheter surface 34 of outercatheter 4 and/or large diameter surface 42 of outer adapter 10, and thedistal end of support sheath 12 is positioned over the proximal end ofballoon 14 with the advantage of strengthening the balloon bond 22 and,if desired, holding balloon 14 below the surface of outer catheter 4.Support sheath 12 can be affixed to external catheter surface 34 and theproximal end of balloon 14, or it may not be affixed to one or bothsurfaces, provided that it does not move with respect to outer catheter4 or balloon 14. Inner catheter 6 extends beyond the distal end of outercatheter 4 and nose cone 60 is affixed to inner catheter 6 at a locationdistal to the distal end of outer catheter 4. In this embodiment, theballoon sits in a pocket between the distal end of outer catheter 4 andthe proximal end of nose cone 60 with the advantage of positioning theballoon bond lower than (i.e. radially inward from) the outer diameterof outer catheter 4 and, if desired, the balloon outer diameter, when inits unexpanded configuration, can be positioned so that it issubstantially equal to or less than the outer diameter of the outercatheter 4. In this manner, a balloon, when in its unexpandedconfiguration, can be positioned within a pocket at or below the outersurface of outer catheter 4, expand to a diameter greater than outercatheter 4, and then return, upon deflation, to a diameter less than orequal to the outside diameter of outer catheter 4. The proximal end ofcatheter assembly 58 is in fluid communication with the interior spaceof balloon 14 by way of annular lumen 18 and adapter 10 at fluid channel20 which is defined by an annular space between the inner surface ofsmall diameter surface 44 of adapter 10 and the outer surface of innercatheter 6. Alternate configurations of this embodiment include use ofadapter 10 and without the support sheath 12 or use of the supportsheath 12 without the adapter 10. When only the support sheath 12 isused, the outer diameter of proximal balloon 14 is bonded to the innersurface of the support sheath 12. Another configuration of thisembodiment includes the use of an outer adapter to affix the balloon tothe nose cone 60 or the use of a support sheath to affix balloon 14 tonose cone 60 or the use of both an adapter and support sheath to affixballoon 14 to nose cone 60. Optimally, balloon 14, adapters, supportsheaths and none cone 60 have an outer diameter equal to or less thanthe outer diameter of outer catheter 4.

Referring to FIGS. 6A and 6B, a third embodiment of the device of thepresent disclosure is shown with catheter assembly 62, outer catheter 4,inner catheter 6, outer adapter 10, large diameter surface 42, smalldiameter surface 44, support sheath 12, fluid channel 20, balloon 14,proximal balloon bond 22, distal balloon bond 24, second outer catheter64, distal outer adapter 66, large diameter surface 68, small diametersurface 70 and second support sheath 72. Inner catheter 6 extends beyondthe distal end of outer catheter 4 and second outer catheter 64 may beaffixed to inner catheter 6 at a location distal to the distal end ofouter catheter 4, whereby balloon 14 is disposed in a pocket between thedistal end of outer catheter 4 and the proximal end of second outercatheter 64 with proximal balloon bond 22 and distal balloon bond 24positioned below the surface of outer catheter 4 and second outercatheter 64. In one construction of the present embodiment, balloon 14is configured with an outer diameter less than or equal to the outerdiameter of catheter 4 and second outer catheter 64 and thereby isconcealed within a pocket therebetween. When inflated to its radiallyexpanded configuration, balloon 14 will have a diameter greater than theoutside diameters of outer catheter 4 and second outer catheter 64 andextend radially outward from said pocket. When balloon 14 is thendeflated from its radially expanded configuration it will return to adiameter less than or equal to outer catheter 4 and second outercatheter 64 and again be concealed within the pocket. The externalcatheter surface 34 at the distal end of outer catheter 4 is bonded tothe inner surface of large diameter surface 42 of adapter 10. Theproximal end of balloon 14 is bonded at its inner surface to the outersurface of small diameter surface 44 of outer adapter 10 and the distalend of balloon 14 is bonded at its inner surface to the outer diameterof small diameter surface 70 of distal second adapter 66. Alternately,the inner luminal surface of balloon 14 can be bonded at its distal enddirectly to inner catheter 6. The inner diameter of large diametersurface 68 of distal adapter 66 is bonded, reflowed, compressed orotherwise affixed to the proximal end of a second outer catheter 64. Aflow channel between the inner surface of small diameter surface 70 ofsecond adapter 66 and inner catheter 6 may or may not be present. In thecase where one balloon is present the distal end of the balloon will besealed. However, if a second balloon is positioned distal to a firstballoon, then a flow channel may be configured to allow inflation anddeflation of a second, third, fourth or any number balloons and it isunderstood that any number of balloons and outer catheter segments canpositioned in series. A first support sheath 12 may be positioned suchthat it extends over the outer surface of the distal end of outercatheter 4 and the proximal end of balloon 14 and a second supportsheath 72, may be positioned such that it extends over the outer surfaceof the proximal end of second outer catheter 64 and the distal end ofballoon 14. Support sheaths 12 and 72 can be bonded, glued, reflowed,compressed or otherwise affixed to the distal end of outer catheter 4 orproximal end of second outer catheter 64 and may, if desired, be affixedto balloon 14. Support sheath 12 provides the advantage of restrainingor compressing the proximal end of balloon 14 at the proximal balloonbond 22 and strengthening the balloon bond and preventing detachment. Asecond support sheath 72 adds the advantage of retaining or compressingballoon 14 at distal balloon bond 24 or strengthening the balloon bondand preventing detachment. The proximal end of catheter assembly 62 isin fluid communication with the interior space of balloon 14 by way ofannular lumen 18 and outside adapter 10 at fluid channel 20, which isdefined by an annular space between the inner surface of small diametersurface 44 of adapter 10 and the outer surface of inner catheter 6 asseen by flow path 26. Alternate configurations of this embodimentinclude an outer adapter 10 without a support sheath 12, a supportsheath 12 without adapter 10, outer adapter 66 without second supportsheath 72, second support sheath 72 without outer adapter 66 or anycombination of adapters and support sheaths, provided that the proximalend and distal end of balloon 14 have at least one adapter or sheath orare bonded directly to inner catheter 6 and annular lumen 18 is in fluidcommunication with the interior surface of balloon 14. Optimally,balloon 14, both support sheaths and both adapters have an outerdiameter equal to or less than the outer diameters of outer catheter 4and second outer catheter 64 of catheter assembly 62, although there isno requirement for balloon 14 to be constrained below the surface ofcatheter assembly 62, provided that bonding surfaces 22 and/or 24 arepositioned below the outer surface of catheter assembly 62. It would beparticularly useful when delivering therapy in small vessels, for aballoon or other accessory or tool to be positioned below the surface ofa catheter, in its unexpanded state, and then following inflation ordeployment be returned to the same position below the catheter surface.

Referring now to FIGS. 7A and 7B, a longitudinal cross section of yetanother embodiment of the present disclosure is shown with catheterassembly 74, outer catheter 4, inner catheter 6, proximal inner adapter46, large diameter surface 48, small diameter surface 50, fluid channel76, distal inner adapter 78, large diameter surface 80, small diametersurface 82 and support sheath 86. In this embodiment, inner adapters 46and 78 are used instead of outer adapters whereby the outer surfaces oflarge diameter surfaces 48 and 80 of inner adapters 46 and 78 are bondedor otherwise affixed to the inner circumference of outer catheter 4 andthe inner circumference of second outer catheter 84. In this embodiment,the balloon 14 is disposed in a pocket between the distal end of outercatheter 4 and the proximal end of second outer catheter 84. It isunderstood that any combination of adapters and support sheaths can beused. The proximal and/or distal balloon bonds are positioned below theouter surfaces of outer catheter 4 and second outer catheter 82 andfluid communication is maintained from the proximal end of catheterassembly 74 and the interior surface of the balloon 14 by way of annularlumen 18 and adapter 46 at fluid channel 76 which is defined by anannular space between the inner surface of small diameter surface 50 ofadapter 46 and the outer surface of inner catheter 6. It is alsounderstood that a nose cone or other nose piece can be affixed to alocation distal to the second outer catheter 84 and that any number ofballoons and outer catheter segments can be serially oriented alongcatheter assembly 74.

Referring now to FIGS. 8A and 8B, yet another embodiment of the presentdisclosure is shown with catheter assembly 88, two lumen catheter 90,injection lumen 92, balloon inflation lumen 94, injection lumenextension 96, nose cone 98, outer adapter 100, large diameter surface102, small diameter surface 104, support sheaths 106 and 108, balloon110, proximal balloon bond 112, distal balloon bond 114, fluid channel116 and flow path 118. In this instance, a single catheter with 2 lumensis used instead of the two catheter coaxial construction as described inthe above embodiments. While a two lumen catheter is useful for numerousapplications, the catheter can also include 3, 4, 5 or more lumens asneeded. Catheter assembly 88 can be any length useful for medicalapplications, typically from 25 cm to 250 cm, more typically from 50 cmto 150 cm. Injection lumen 92 has a proximal end and a distal end andextends from the proximal end of catheter assembly 88 to the distal endof catheter assembly 88 and provides fluid communication therebetween.Balloon inflation lumen 94, has proximal and distal ends and extendsfrom the proximal end of catheter assembly 88 to balloon 110, providinga means for inflation and deflation. Injection lumen 92 extends distallybeyond the distal end of two lumen catheter 90 and distally beyond theend of balloon lumen 94 as illustrated by injection lumen extension 96and length 120. The injection lumen extension typically has a length inthe range of 0.1 cm to 50 cm, more typically from 1 cm to 10 cm. Nosecone 98 is positioned about the injection lumen extension 96 at a pointthat is distal to the distal end of two lumen catheter 90, wherebyballoon 110 is disposed in a pocket between the distal end of two lumencatheter 90 and the proximal end of nose cone 98. Nose cone 98 istypically placed at a distance of 0.25 cm to 10 cm, more typically from1 cm to 3 cm from the distal end of two lumen catheter 90 and can be anyshape or configuration and can be composed of any convenient materialincluding materials that are radiopaque. For illustration only, theembodiment of FIGS. 8A and 8B includes outer adapter 100 and bothproximal and distal support sheaths 106 and 108, however any combinationof adapters and support sheaths can be used, provided that fluidcommunication is maintained between the inflation lumen 94 and theinterior surface of balloon 110. Outer adapter 100 has a large diametersurface 102 and a small diameter surface 104, whereby the inner surfaceof large diameter surface 102 is bonded to the distal outer surface oftwo lumen catheter 90 and the small diameter surface is oriented aboutinjection lumen extension 96, such that an annular space between theinner surface of small diameter surface 104 and injection lumenextension 96 is maintained. The proximal end the catheter assembly 88 isin fluid communication with the interior space of balloon 110 by way ofballoon inflation lumen 94, outer adapter 100, an annular space betweenthe injection lumen extension 96 and the inner surface of the smalldiameter surface 104 of adapter 100, defined by fluid channel 116 andflow path 118. In most cases it is desirable that the central injectionlumen 92 allow fluid communication therethrough, however, this is not arequirement. In some uses, the injection lumen 92 can be a solid andwithout fluid communication, thereby configuring a one lumen ballooncatheter. It may also be desirable for balloon 110 to sit below theouter diameter of catheter assembly 88, however this is not required. Insome embodiments, balloon 110 does not sit below the outer diameter ofcatheter assembly 88, but at least the proximal balloon bond 112 ispositioned below the outer diameter of catheter assembly 88.

Referring now to FIGS. 9A and 9B, an embodiment is shown comprising aballoon mediated steerable catheter. As shown in FIG. 9A, a catheter tipmay be provided with a balloon 130 near its distal tip 132, similar oridentical to the configurations previously described. The balloon 130may be inflated as shown past a diameter needed to occlude a small bloodvessel such that it bulges laterally to one side of the catheter tip 132as shown. This off-center state of balloon 130 forces the distal tip 132of the catheter to bend laterally in the opposite direction around a“bend point” 134. The degree of bend or bend angle of distal tip 132 isa function of the volume of fluid in balloon 130. This arrangement canbe used as a means to steer a catheter around a sharp turn.

FIG. 9B depicts various angles that catheter tip 132 may bend away fromthe longitudinal axis of the main catheter. As balloon 130 isprogressively inflated with more fluid, tip 132 may bend from a straightorientation (a) through various acute angles (b), (c) and (d), to aright angle (e) and to obtuse angles (f) and (g), as shown.

According to some embodiments, a protocol for advancing the catheteraround a sharp turn comprises the following steps:

-   -   1) track the catheter over a guidewire to the vascular branch or        sharp angle;    -   2) withdraw the guidewire just enough to position the distal tip        of the guidewire to a position proximal to the catheter bend        point 134;    -   3) inflate the balloon 130 and visualize the direction that the        catheter tip 132 is bending, such as by using fluoroscopy;    -   4) rotate the catheter axially such that tip 132 is pointed in        the desired direction;    -   5) further inflate or deflate balloon 130 until catheter tip 132        is pointed into the desired branch artery;    -   6) advance the guidewire into the branch artery;    -   7) advance the catheter over the guidewire into the branch        artery; and    -   8) deflate the balloon and continue to advance the catheter over        the guidewire.

In some protocols, a contrast agent can be injected through the distaltip 132 of the catheter and fluoroscopy can be used to visualize thetarget vessel.

Balloon 130 may be configured with a uniform wall thickness, or it maybe provided with a thinner wall thickness on one side to ensure that itinflates laterally to the same side every time. In some embodiments, thewall thickness may be varied to provide a desired shape or inflationprofile. In some embodiments the balloon is configured to surround thecircumference of the catheter, and in other embodiments it can beattached to only one side of the catheter. In embodiments that utilize aballoon that surrounds the catheter, an adhesive may be used between oneside of the catheter and part of the inside surface of the balloon toensure that the balloon does not inflate on that side.

In some embodiments, bend point 134 is the midpoint of a curve. Thecurve may have a radius of 50 mm, 25 mm, 10 mm or less. The catheter maybe modified at bend point 134 to allow the catheter to bend with lessforce applied by balloon 130. For example, the catheter may have areduced diameter and/or wall thickness at one or more locations tofacilitate easier bending and/or a smaller radius of curvature. In someembodiments, the bend point can be varied by advancing or retracting aguidewire within the catheter, such that the catheter starts bendingjust beyond the distal end of the guidewire.

As used herein, the word “about” means plus or minus 10% of a nominalvalue, unless the particular context indicates otherwise. In view of theteachings herein, many further embodiments, alternatives in design anduses of the embodiments of the instant disclosure will be apparent tothose of skill in the art. As such, it is not intended that theinvention be limited to the particular illustrative embodiments,alternatives, and uses described above but instead that it be solelylimited by the claims presented hereafter.

What is claimed is:
 1. A method of using a balloon catheter assembly,the method comprising: providing a balloon catheter assembly, theassembly comprising: an outer catheter having a proximal end and adistal end, the distal end of the outer catheter having a wallthickness, the outer catheter comprising at least two layers including abraided, coiled or woven reinforcing layer and a base layer, the outercatheter having an outer diameter that does not step down at the distalend of the outer catheter; an inner catheter located coaxially within alumen of the outer catheter, the inner catheter having an injectionlumen extending therethrough, the inner and outer catheters forming aninflation lumen therebetween; an outer adapter having a length less than25 mm, a proximal end and a distal end, the proximal end of the outeradaptor being sized to fit over an outside surface of the distal end ofthe outer catheter and configured to be affixed thereto, the distal endof the outer adapter having a reduced outer diameter portion that issmaller than the outer diameter of the outer catheter at the distal endof the outer catheter, the distal end of the outer adapter having aninside diameter that is larger than an outer diameter of the innercatheter, thereby forming a fluid channel therebetween that is in fluidcommunication with the inflation lumen, the outer adapter having a wallthickness that is between 0.001 mm and 0.005 mm and is thinner than thewall thickness of the distal end of the outer catheter, the outeradapter not having a braided, coiled or woven reinforcing layer; and aballoon having a proximal end with an inner surface affixed to thereduced outer diameter portion of the outer adapter, the balloon havinga distal end with an inner surface affixed to the outer diameter of theinner catheter, the balloon having an interior space that is in fluidcommunication with the fluid channel, the proximal end of the balloonbeing less than 25 mm away from the distal end of the outer catheter;inserting a distal end of the balloon catheter assembly into a bloodvessel of a body; inflating the balloon by introducing a fluid throughthe inflation lumen and the fluid channel into the interior space of theballoon to at least partially occlude blood flow in the blood vessel;injecting a substance into the blood vessel through the injection lumen;deflating the balloon by removing the fluid from the interior space ofthe balloon such that the balloon returns entirely within apredetermined volume having an outer diameter substantially equal to orless than the outer diameter of the outer catheter at the distal end ofthe outer catheter; and withdrawing the distal end of the ballooncatheter assembly from the blood vessel.
 2. The method of claim 1,wherein the inner catheter has a distal end that extends distally beyondthe distal end of the balloon.
 3. The method of claim 2, wherein theballoon catheter assembly further comprises a nosecone located on thedistal end of the inner catheter distal to the balloon, the noseconehaving an outer diameter substantially equal to the outer diameter ofthe outer catheter at the distal end of the outer catheter such that theballoon is recessed in a pocket formed between the nosecone and theouter catheter when the balloon is in a deflated configuration.
 4. Themethod of claim 1, wherein the balloon catheter assembly furthercomprises a proximal bond that affixes the inner surface of the proximalend of the balloon to the reduced outer diameter portion of the outeradapter, and a distal bond that affixes the inner surface of the distalend of the balloon to the outer diameter of the inner catheter.
 5. Themethod of claim 4, wherein both the proximal bond and the distal bondare located radially inward from the outer diameter of the outercatheter at the distal end of the outer catheter.
 6. The method of claim5, wherein both the proximal bond and the distal bond are locatedradially inward from an inside diameter of the outer catheter at thedistal end of the outer catheter.
 7. The method of claim 1, wherein theinflation lumen has a substantially annular cross-section.
 8. The methodof claim 1, wherein the outer catheter comprises a base material and adifferent reinforcing material, and the outer adapter is made of aplastic polymeric material.
 9. The method of claim 1, wherein the outeradapter has been attached to the distal end of the outer catheter usinga reflow process.
 10. The method of claim 9, wherein the outer diameterof the outer catheter at the distal end of the outer catheter has notbeen increased by the addition of the outer adapter after the reflowprocess.
 11. The method of claim 1, wherein the balloon catheterassembly further comprises a support sheath disposed over andcompressing the proximal end of the balloon.
 12. The method of claim 11,wherein the support sheath is composed of a single layer flexiblematerial with a wall thickness and a material composition that are thesame as those of the outer adapter.